So I heard this one while I was in technical school for the Air Force back in 2010. The base I was at had training for aircraft weapons maintainers, crew chiefs, medical, and dental. This version of the legend came from the dental side; same thing, a student kept waking up with a sore rear, couldn't figure out why, so he set up his webcam to record all night, turns out his roommate was sneaking into the chemicals that the dental schoolhouse supposedly had on hand and was administering ether to his roommate in order to have his way with him. Again, following the legend, the guy pretends to go to sleep and, when his roommate comes up to him to knock him out, he beats the crap out of him with a bat. We had the awesome addition of the perpetrator having the nickname "The Ether Bunny".